Safety joint



Jn 12 1937-` ELBURNs 'Er-AL y 2,067,3 7T SAFETY Jom 4 l Filed Aprile, les;

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Arme/Vey `Patented jan. 12, 1937 PATENT OFFICE SAFETY JOINT I Erwin Burns and Harry P. Wiekersham, Los Angeles, Calif.

Application April 2, 1935, Serial No. 14,243

9 claims. (o1. 255-28) This invention relates to oil well drilling equipment and particularly pertains to a safety joint.

, In the operation of oil well drilling which includes a string of drill pipe carrying some appropriate tool at the lower end it is the usual practice to thread the joints of the drill strings together and to set the threads as the drill string is assembled and lowered into the well, so that a positiver action may be accomplished by exertion of torque upon the drill string in `one direction, and by the additional exertion of tension and compression in the drill string as occasion demands. Under some conditions it becomes necessary to disconnectan upper section of drill string from a lower section, and since -it might be possible by reverse rotation of the drill string to unscrew the string at one of its joints, it will be recognized that there would be m) n certainty or selection as to the joint unscrewed, and it is the object of the present invention to provide an instrumentality which may be interposed in the line of drill string at a predetermined pointA and which will permit separation of the drill string at that point without requiring the imposition of suicient torque upon the drill string to unscrew the drill string at any of its joints, the structure having the additional advantages or providing a positive lock between au the sections of the string between which it is positioned so that a positive driving action, as well as torque and tension forces, may be applied to the drill string without throwing a strain on the parts of the structure, the lock being so designed as to'permit its prqperrelease upon reverse rotation of the drill string only.

The invention contemplates the provision of' a. pair of tubular members, one threaded into the other Aand adapted to positively engage each. other when rotated in a Ydriving direction, which Fig. 3 is a view in longitudinal section and'V elevation through the safety joint showing the.

elements .of its assembled structure. i

sa Fig. 4 is avview in transverse section through l members are provided with a temporarypositive the structure as seen on the line 4-4 of Fig. 1, showing the positive lock means.

Figure 5 is a fragmentary. view in elevation showing the developed circumference of the safety yjoint lock portion particularlydisclosing 5 the keys and locking lugs.

'Referring more particularly to the drawing I0 indicates a tool joint at the lower end of a section of drill string. A mandrel II is threaded into the tool joint at itsupper end. This man- 10 drel comprises an upper cylindrical section I2, a lower threaded section I3 and intermediate lugs It formed integral therewith. The threaded section I3 is preferably formed with square threads having considerable strength and which threads 15 screw into a sleeve or box I5. The lower end of the sleeve is formed with al threaded pin I6 adapted to be positioned within the threaded end'of a tool joint not shown in the drawing. The threaded bore of the sleeve I5 terminates 20 in a cylindrical portion I1 which receives a cylindrical extension I8 of the mandrel I3. An annular packing groove I9 is formed around the extension portion I8 and receives a packing ring 20. Fluid ducts 2| are formed through the inner wall of the packing groove I 9 so that uid under pressure may act against the packing rings and form a iiuid seal with the cylindrical bore I1. A central uid circulating bore 22 extends longitudinally through the entire mandrel II. The pin portion I6 of the sleeve I5 is formed with a central passageway 23 through which uid, may ilow from the passageway 22l of the mandrel. 'Ihe lugs I4 are formed integral with y the entire mandrel structure and are interposed 35 between the cylindrical section I2 and the threaded portion I3. The under face of the lugs I4 are disposed at an angle agreeing with that of the thread pitch and the upper face of sleeve. I5. It is also formed in stepped planes as shown in Figure 5 causing shoulders 24 to be disposed upon diametrically opposite sides of the under face of the collar, as will be hereinafter explained. These shoulders 24 engage upwardly projecting driving shoulders 25 formed on the 45 upper end' face of the sleeve I5, and which face is complementary to the under face of lugs I4. These driving shoulders provide means for posi`` tively driving the mandrel |I.an d the sleeve I5 in unison. It will be evident that when the threaded member I3 is firmly screwed intothe sleeve I5 .the lower face or faces of the lugs I4 will register with the upper face or faces of the sleeve I5 and the shoulders 25 will be in engagement'with the arcuate recesses 24. occurring 55 a helical spring 29, which circumscribes the cylindrical portion I2 of the mandrel II and is interposed between the end face of the tool joint I and the upper face of-the lock ring 28. The lower end of each of the keys 21 is formed with a V-shaperlipoint 30, having a relatively long flat face 3| in the direction of rotation of the tool and a relatively short sharp face 32 completing the point. Complementary V-shaped grooves 33 are formed in the upper end face of the sleeve I5. This. makes its possible for a cam action to be obtained between the keys and the sleeve against the expansive action of the spring 29 when counter rotation ofthe upper drillstring section is brought about.

In operation of the present invention the device is constructed and assembled as shown in Fig. 3 of the drawing. In the locking position all of the elements are as shown in Figs. 1 and l3 of the drawing. Here it will be seen that the spring 29 holds the lock ring 28 in a seated position against the upper face of the lugs I4 and that the lower face of the lugs I4 are in a seated position against the upper face of the sleeve I5. When the tool is being operated it is being driven in a clockwise direction and under such circumstances the radial shoulders 2liy of the lugs I4 vengage complementary abutting shoulders 25 of the sleeve I5. When in this position compression or tension strains may be exerted upon the drill string without any possibility of creating' a disengaging movement between 'the locked parts `of the safety joint'. In the event that it is desired to disengage parts of the safety joint, the drill string and the tool joint I0 are rotated`ina counter-.clockwise direction. This will force the mandrel II to rotate counterclockwise, tending to rotate the ring 23, the keys 21 of which are in engagement with the longitudinal keyways 26 occurring between the lugs I4. The mandrel will be resistant to reverse rotation due to the fact that the inclined faces 32 of the tongues must be forced upwardly along the inclined faces 32' of the notches 33.` As this upward movement takes place, as shown in Fig. 2 of the drawing, the shoulders 24 and shoulders 25 will separate as the lugs I4 move upwardly and away from the sleeve I5 due to the threaded engagementof the screw portion I3 with the sleeve I4. The amount of force required to 'produce this action will be that which is needed to cause the faces 32 and 32 of the keys. 21 and the notches 33 to slide with relation to each other against the expansive action of the spring 29. In this manner the driving shoulders 24 of the collar I4 will move out of driving engagement with the shoulders 25 upon the upper face of vabsage?? understood that various changes might be made in the combination, construction, and arrangement of parts, by those skilled in the art, without departing lfrom the spirit of the invention as claimed.

Having thus described our invention, what we claim and desire to secure by Letters Patent is:

1. A safety joint including a tubular member Ahas been exerted thereon.

2. A safety joint including two members adapted to be connected with sections of a drill string, a threaded connection between said members by which they are held in assembled position relative to each other, means providing a positive drivingl connection in one direction between said members when thus assembled, lock means positively engaging one of said members at all times and yieldably engaging the other of said members, and 'cooperating means between the engaging portion of the lock means and the last mentioned member whereby a movement in a reverse direction from that of driving rotation will cause said members to become disengaged under'a predeterminedY degree of torque to permit unthreading of the two main members with relation to each other.

3. A safety joint including two main sections, a

'threaded connection between said sections,

suming positions in positive driving relation to55 each other when said members are assembled. a

clutch member relatively movable with relation to the sleeve and positively engaging the mandrel for holding said mandrel and sleeve against' clutch to determine the magnitude of countertorque required to produce said release.

5. A safety joint including a. pair of sectionsl having threaded engagement with each other and disposed in driving relation to drill string sections, a pair of driving shoulders one on each v of said sections and adapted to positively engage each other when the' sections are in their assembled threaded positions, lock means mounted on. one of said sections for yieldable movement relative tothe other of said sections, said lock I means and said last namedsection engaging each other in a mannervto permit their release upon counter rotation of one section with relation to the other, and yleldable means acting upon said lock means to establish the counterrotational force necessary to create disengagement of the lock means and the main section engaged thereby and thereafter to permit disengagement of the drive shoulders and unthreading of the parts with relation to each other.

6. A safety joint including a tubular section connected to a lower length of drill string, a mandrel section connected to an upper length of drill string, a shoulder on the mandrel section, a threaded portion occurring below the shoulder and adapted to be threaded into the tubular section whereby in its assembled position the lower face oi' the shoulder will abut against the upper face of the tubular section, positive drive shoulders formed upon said abutting sections whereby positive drive torque may be imposed from the mandrel to the sleeve when said sections are in engagement, and yieldable lock means temporarily holding the said driving -faces in their engaged position to resisteounterrotation vof the mandrel with relation to the sleeve until a predetermin d -magnitude of counter-torque has -been set p.

7. A safety joint including a tubular section connected to a lower length of drill string, a

l mandrel section-connected to" an upper length of drill string, a shoulder on the mandrel section,- av threaded portion occurring below the shoulder and adapted to be threaded into the tubular'section whereby in its assembled position the lower face of the shoulder will abut against the upper `face of the tubular section,

positive drive shoulders formed upon saidvabuif ting sections whereby positive be imposed from the mandrel to the sleeve when said sections are in engagement, yieldable lock means temporarily holding the said driving facesv in their engaged position to resist counterrotation of the mandrel with relation to the sleeve until a predetermined magnitude of scounter-torque has been set up, said yieldable' lock means including means constantly and positively engaging the mandrel and engaging the sleeve with sliding friction, and .spring means acting upon the lock means to control the amount of sliding friction required to produce drive r u to q e may aforesaid assembling disengagement of the lock means with relation to the sleeve. l

8. A safety joint including a tubular section said sections are in engagement, yieldable loci:4

means temporarily holding the said driving faces in their engaged position to resist counterrotation of the mandrel with relation to the sleeve until a predetermined .magnitude of counter-torque has been set up, said yieldable lock means including means constantly and positively engaging the mandrel and engaging the sleeve with sliding friction, and spring means acting upon the lockl means tov control the amount of sliding friction required to produce disengagement of the lock means with relation to the'sleeve, said sliding friction being produced by an inclined face on the lock means engaging an inclined face on the sleeve.

9. A safety joint including a tubular member carried at the upper end of a string of pipe, a mandrel carried at thelower end of a complementary string of pipe, means producing a positive threaded engagement between the mandrel and the tubular member, means for positively drivingthe tubular member in one direction by the mandrel when said members are in the and threaded position, separate lock means for temporarily holding the mandrel and the tubular'member in their locked position 'when the mandrel is rotated in a counter-direction until a predtermlned torque force has been exerted thereon, said mandrel 45. the safety joint and packingA 

